Self-assembled rows of Ni porphyrin dimers on the Ag(111) surface

Abstract

The growth and ordering of 5-(10,15,20-triphenylporphyrinatonickel(ii))dimer (NiTPP-dimer) molecules on the Ag(111) surface have been investigated using scanning tunnelling microscopy/spectroscopy (STM/STS) and low-energy electron diffraction (LEED). At one monolayer (ML) coverage the NiTPP-dimer forms a well-ordered close-packed molecular layer in which the porphyrin molecules have a flat orientation with the molecular plane lying parallel to the substrate. STM and LEED data obtained from one monolayer of the NiTPP-dimer on the Ag(111) surface show the formation of three domains which grow along the main crystallographic directions of the substrate. Scanning tunnelling spectroscopy data obtained from the NiTPP-dimer on the Ag(111) surface show good agreement with optical band gap measurements and density functional theory calculations.

Self-assembly and ordering of C60 on the WO2/W(110) surface

“…This controlled self-assembly of organic nanostructures offers a number of powerful approaches for the development of organic molecule-based devices, which possess functions such as rectifying, switching and sensing [1][2][3][4][5][6][7][8][11][12][13]. Fullerenes have attracted considerable attention in recent years due to their potential in surface chemistry and nanotemplating [13], non-linear optics [13,14], single-molecule transistors [11,15], and especially molecular electronics because of their tunable electronic properties, resulting in superconducting or semiconducting behaviour [11,16,17].…”

“…The fabrication of complex organic molecular structures on technologically important substrates held together by weak and reversible van der Waals interactions, hydrogen bonds or electrostatic interactions has been a much investigated topic in the past ten years [1][2][3][4][5][6][7][8][9][10]. This controlled self-assembly of organic nanostructures offers a number of powerful approaches for the development of organic molecule-based devices, which possess functions such as rectifying, switching and sensing [1][2][3][4][5][6][7][8][11][12][13].…”

Growth and ordering of Ni(II) diphenylporphyrin monolayers on Ag(111) and Ag/Si(111) studied by STM and LEED

“…This is a result of significant rotation of the phenyl rings, imaged as oval protrusions (figures 1a and 1b). The plane of the phenyl rings is usually rotated by approximately 60º with respect to the macrocycle plane according to ab initio calculations, STM and x-ray absorption experiments [24,30,37,38]. Such rotation allows the NiDPP molecules to approach each other on the surface in a specific manner and form an extended close-packed structure to minimize the surface energy.…”

“…Furthermore, they are essential to various natural biological processes as the main functional groups of haemoglobin and chlorophyll. To this end, porphyrin derivatives have been used to prepare a rich variety of molecular nanostructures such as clusters, wires and extended networks on different surfaces [6,[15][16][17][18][19][20][21][22][23][24][25][26]. Such nanostructures offer a number of powerful approaches for the development of molecule-based devices [1][2][3].…”

“…The Ag/Si(111)-(√3 × √3)R30º surface was chosen since the porphyrin-substrate interaction is expected to be intermediate in strength between that of the clean Si surfaces and the Ag(111) (or hydrogen-passivated Si) [23,24,[27][28][29][30]. On the former surface the molecules form covalent bonds and are unable to diffuse and self-assemble into ordered structures at room temperature [30], while on the latter the molecules diffuse freely and may form islands [23,24,[27][28][29]. The results of this work yield important information on the conformational behaviour and structural properties of the NiDPP monolayers depending on the porphyrinsubstrate interaction.…”